When we see records being broken and unprecedented events such as this, the onus is on those who deny any connection to climate change to prove their case. Global warming has fundamentally altered the background conditions that give rise to all weather. In the strictest sense, all weather is now connected to climate change. Kevin Trenberth

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Britain's security service, the MI5, warned British businesses of threat of Chinese cyber spying, calling China “one of the most significant espionage threats” to Britain

LONDON — British business executives dealing with China were given a formal warning more than a year ago by Britain’s security service, MI5, that Chinese intelligence agencies were engaged in a wide-ranging effort to hack into foreign companies’ computers and to blackmail foreign businesspeople over sexual relationships and other improprieties, according to people familiar with the MI5 document.

The warning, in a 14-page document titled “The Threat from Chinese Espionage,” was prepared in 2008 by MI5’s Center for the Protection of National Infrastructure, and distributed in what security officials described as a “restricted” form to hundreds of British banks and other financial institutions and businesses. The document followed public warnings from senior MI5 officials that China posed “one of the most significant espionage threats” to Britain.

Details of the document were confirmed Sunday by two people familiar with its contents, both of whom spoke on an anonymous basis because of the sensitivity of the subject. The document’s existence was first reported in the weekend editions of the British newspaper The Sunday Times.

Last month Google announced it was considering ending its operations in China following a “sophisticated and targeted” cyberattack that it said aimed primarily to access the e-mail accounts of Chinese human rights activists. Google said it was no longer willing to cooperate with China in what amounted to censorship of its search engine, which Google had operated in a way that prevented millions of Chinese from accessing Web sites deemed hostile by Chinese authorities.

Secretary of State Hillary Rodham Clinton has called on China to investigate the cyberattacks, and said that companies like Google should refuse to support “politically motivated censorship.” Without acknowledging any government involvement in the attacks, China has responded by saying that Internet companies like Google are welcome to do business in China “according to the law.” A Foreign Ministry spokesman said that “Chinese law proscribes any form of hacking activity.”

But a starkly different picture emerges from the document circulated by MI5, Britain’s domestic security service. The Sunday Times account, quoting from the document, said that officers from the People’s Liberation Army and the Ministry of Public Security had approached British businesspeople at trade fairs and exhibitions with offers of “gifts” that included cameras and computer memory sticks that were found to contain bugs that provided the Chinese with remote access to the recipients’ computers.

“There have been cases where these ‘gifts’ have contained Trojan devices and other types of malware,” the document said, according to The Sunday Times. The accuracy of the paper’s citations from the document was verified by the two people contacted by The New York Times who said they had seen the document.
The MI5 report described how China’s computer hacking campaign had attacked British defense, energy, communications and manufacturing companies, as well as public relations companies and international law firms. The document explicitly warned British executives dealing with China against so-called honey trap methods in which it said the Chinese tried to cultivate personal relationships, “often using lavish hospitality and flattery,” either within China or abroad.

“Chinese intelligence services have also been known to exploit vulnerabilities such as sexual relationships and illegal activities to pressurize individuals to cooperate with them,” it warned. “Hotel rooms in major Chinese cities such as Beijing and Shanghai which have been frequented by foreigners are likely to be bugged. Hotel rooms have been searched while the occupants are out of the room.”

Britain’s powerful Joint Intelligence Committee, responsible for analyzing and coordinating policy between MI5 and MI6, the Secret Intelligence Service that is responsible for Britain’s foreign intelligence activities, warned last year that China’s growing sophistication in cyberespionage could enable it to shut down critical services, including power, food and water supplies.

Reports

Wetlands are the largest individual source of methane (CH4),but the magnitude and distribution of this source are poorlyunderstood on continental scales. We isolated the wetland andrice paddy contributions to spaceborne CH4 measurements over2003–2005 using satellite observations of gravity anomalies,a proxy for water-table depth , and surface temperature analysesTS. We find that tropical and higher-latitude CH4 variationsare largely described by and TS variations, respectively. Ourwork suggests that tropical wetlands contribute 52 to 58% ofglobal emissions, with the remainder coming from the extra-tropics,2% of which is from Arctic latitudes. We estimate a 7% risein wetland CH4 emissions over 2003–2007, due to warmingof mid-latitude and Arctic wetland regions, which we find isconsistent with recent changes in atmospheric CH4.

1 School of GeoSciences, University of Edinburgh, Edinburgh, U.K.2 SRON Netherlands Institute for Space Research, Utrecht, The Netherlands.

The wisdom of Solomon

A quick post for commentary on the new Solomon et al paper in Science Express. We’ll try and get around to discussing this over the weekend, but in the meantime I’ve moved some comments over. There is some commentary on this at DotEarth, and some media reports on the story – some good, some not so good. It seems like a topic that is ripe for confusion, and so here are a few quick clarifications that are worth making.
First of all, this is a paper about internal variability of the climate system in the last decade, not on additional factors that drive climate. Second, this is a discussion about stratospheric water vapour (10–15 km above the surface), not water vapour in general. Stratospheric water vapour comes from two sources – the uplift of tropospheric water through the very cold tropical tropopause (both as vapour and as condensate), and the oxidation of methane in the upper stratosphere (CH4+2O2 –> CO2 + 2H2O; NB: this is just a schematic, the actual chemical pathways are more complicated). There isn’t very much of it (between 3 and 6 ppmv), and so small changes (~0.5 ppmv) are noticeable.

The decreases seen in this study are in the lower stratosphere and are likely dominated by a change in the flux of water through the tropopause. A change in stratospheric water vapour because of the increase in methane over the industrial period would be a forcing of the climate (and is one of the indirect effects of methane we discussed last year), but a change in the tropopause flux is a response to other factors in the climate system. These might include El Nino–La Nina events, increases in Asian aerosols, or solar impacts on near-tropopause ozone – but this is not addressed in the paper and will take a little more work to figure out.

The study includes an estimate of the effect of the observed stratospheric water decadal decrease by calculating the radiation flux with and without the change, and comparing this to the increase in CO2 forcing over the same period. This implicitly assumes that the change can be regarded as a forcing. However, whether that is an appropriate calculation or not needs some careful consideration. Finally, no-one has yet looked at whether climate models (which have plenty of decadal variability too) have phenomena that resemble these observations that might provide some insight into the causes.

Copenhagen: what next?

It's coming up to six weeks since the end of the Copenhagen negotiations on climate change. Now that the dust has settled, there's time to stand back and take a more considered look. Here Yvo de Boer, executive secretary of the United Nations Framework Convention on Climate Change (UNFCCC), and Stefan Rahmstorf, professor of physics of the oceans at Potsdam University, Germany give their views on the outcome of the COP15 talks and the way forward

At a press conference last week, de Boer said that the outcome in Copenhagen made "the task to hand more urgent…the window of opportunity we have to come to grips with this issue is closing faster than it was before." But he claimed that the talks did raise climate-change issues to the highest level of government, helped to define temperature limits and financial contributions, and set 2015 as a date for reviewing whether global action needs to be more urgent.

The Copenhagen Accord, meanwhile, an agreement negotiated by China, South Africa, India, Brazil and the US, and noted by the other nations at the conference, "reflects a political consensus on the long-term global response" that is needed to climate change, according to de Boer. "We are now in a cooling off period," he added. "This gives useful time for countries to resume discussions with each other."

Climate scientist Stefan Rahmstorf thinks that the outcome of COP15 is depressing, but also tried to highlight some more upbeat aspects. "On the positive side: most of the actors in Copenhagen by far were quite willing to commit to a substantial effort to halt global warming – including many who were not willing to do this earlier, for example the US or Australia," he told environmentalresearchweb. "And some important developing countries have made very constructive pledges as well. We were closer than ever to major progress in fighting global warming."

Rahmstorf reckons that an agreement was not reached because "the consensus-based UN process with 192 ountries is very cumbersome, and it was exceptionally badly managed at this conference," because China did not play a very constructive role and because the US was not able to offer enough. "The IPCC deemed 25–40% emissions reductions below 1990 values necessary by 2020 by developed nations to limit warming to 2 °C, and what the US offered amounted to only 4%," he explained. "This is largely a result of the lost years under previous administrations, during which the US emissions increased steeply – unlike those in Europe."

During his briefing, de Boer said that he never ceases to be amazed by the vision that some people have of the UN. "To me it is a collection of countries that have created a body to facilitate negotiation among each other," he added. "If those governments were to go and negotiate in a different setting with a different secretariat I don't know if that would fundamentally change their behaviour."

Keeping on the UN track
Both de Boer and Rahmstorf would like to see the UN process continue. "Everybody I have spoken to so far doesn't want the Accord to be a third track," said de Boer.

Rahmstorf agrees. "I hope that the multilateral UN track to a global climate agreement will not die, however cumbersome it is, because the alternatives are even worse," he said, "for example, the G20 with only the biggest emitters on the table deciding alone on climate policy, without those affected, like the small island nations, having a proper voice." In the meantime, Rahmstorf says that "while we wait for our world leaders to get their act together, there is nothing to stop us as world citizens to do all we can to reduce emissions bottom-up."

The next UNFCCC negotiating session is due to take place in late May 2010 in Bonn, with the next COP meeting set for Mexico in late November. According to de Boer, many countries feel that there is a need for an intensified negotiating schedule this year – he plans to convene the COP bureau to determine whether it's possible to slot in another set of negotiations before May 2010.

The countries that negotiated the Copenhagen Accord – China, South Africa, India, Brazil and the US – account for around 80% of carbon emissions. "It's true to say there was not final agreement on the Accord, but an overwhelming majority supported it," said de Boer. "It was not formally adopted by COP – only noted – and we should be careful not to make it more than it is."

But de Boer believes the Accord is a political tool that has broad support at a high level and that can be usefully employed in negotiations. He says the Accord is clear on a long-term goal, on how it can be measured, on financial support and on a number of new institutions that need to be established. "It can be used by us to help speed up the negotiations," he said.

Countries have until 31 January to let the UN know if they wish to be associated with the Accord in the official report of the COP15 negotiations. Industrialized countries have the option of including details of the targets they intend to commit to, while developing nations can indicate the action that they plan to take. The deadline is for administrative reasons only; the list of countries associated with the Accord will be updated on the UNFCCC secretariat website as later details come in. "It's a soft deadline, there's nothing deadly about it," said de Boer.

The climate for science
But what does this mean for the day-to-day lives of researchers? Rahmstorf believes the outcome in Copenhagen has no direct or immediate effects on climate science. "The morale of many is shaken, though," he added. "We've got an important job: since the Copenhagen Accord calls for limiting global warming to a maximum of 2 °C, possibly even 1.5 °C (this option is left open at the end of the Accord), one of the major tasks of science will be to narrow down the range of future emissions that is compatible with these policy goals."

Rahmstorf reckons that climate scientists have communicated their work quite well, particularly through the IPCC. While 2010 is the UN year of biodiversity, the biodiversity community has "not yet managed to get as much high-level attention to the biodiversity crisis; it is only now calling to set up something like the IPCC for biodiversity." On the other hand, "climate science could still do a lot better if more climate scientists get involved, take an interest in public understanding of science and educate themselves more about how to effectively work with the media". Rahmstorf reckons that "too many scientists are still stuck in the ivory tower and – for example – shrug off and ignore wrong media reports about climate science, rather than recognizing that public perception matters and that they should not leave the public debate to people with a political agenda."

The last word goes to de Boer: while the Copenhagen negotiations "didn't produce the final cake," they did leave countries "with all the key ingredients to bake a new one." Although the proof of the pudding, as they say, is in the eating.

A 10% drop in water vapour, 10 miles up has had an effect on global warming over the last 10 years, scientists say. Photograph: Getty

Scientists have underestimated the role that water vapour plays in determining global temperature changes, according to a new study that could fuel further attacks on the science of climate change.

The research, led by one of the world's top climate scientists, suggests that almost one-third of the global warming recorded during the 1990s was due to an increase in water vapour in the high atmosphere, not human emissions of greenhouse gases. A subsequent decline in water vapour after 2000 could explain a recent slowdown in global temperature rise, the scientists add.

The experts say their research does not undermine the scientific consensus that emissions of greenhouse gases from human activity drive global warming, but they call for "closer examination" of the way climate computer models consider water vapour.

The new research, led by Susan Solomon, at the US National Oceanic and Atmospheric Administration, who co-chaired the 2007 IPCC report on the science of global warming, is published today in the journal Science, one of the most respected in the world.

Solomon said the new finding does not challenge the conclusion that human activity drives climate change. "Not to my mind it doesn't," she said. "It shows that we shouldn't over-interpret the results from a few years one way or another."

She would not comment on the mistake in the IPCC report -- which was published in a separate section on likely impacts -- or on calls for Rajendra Pachauri, the IPCC chairman, to step down.

"What I will say, is that this [new study] shows there are climate scientists round the world who are trying very hard to understand and to explain to people openly and honestly what has happened over the last decade."

The new study analysed water vapour in the stratosphere, about 10 miles up, where it acts as a potent greenhouse gas and traps heat at the Earth's surface.

Satellite measurements were used to show that water vapour levels in the stratosphere have dropped about 10% since 2000. When the scientists fed this change into a climate model, they found it could have reduced, by about 25% over the last decade, the amount of warming expected to be caused by carbon dioxide and other greenhouse gases.

Solomon said: "We call this the 10, 10, 10 problem. A 10% drop in water vapour, 10 miles up has had an effect on global warming over the last 10 years." Until now, scientists have struggled to explain the temperature slowdown in the years since 2000, a problem climate sceptics have exploited.

The scientists also looked at the earlier period, from 1980 to 2000, though cautioned this was based on observations of the atmosphere made by a single weather balloon. They found likely increases in water vapour in the stratosphere, enough to enhance the rate of global warming by about 30% above what would have been expected.

"These findings show that stratospheric water vapour represents an important driver of decadal global surface climate change," the scientists say. They say it should lead to a "closer examination of the representation of stratospheric water vapour changes in climate models."

Solomon said it was not clear why the water vapour levels had swung up and down, but suggested it could be down to changes in sea surface temperature, which drives convection currents and can move air around in the high atmosphere.

She said it was not clear if the water vapour decrease after 2000 reflects a natural shift, or if it was a consequence of a warming world. If the latter is true, then more warming could see greater decreases in water vapour, acting as a negative feedback to apply the brakes on future temperature rise.

Surface melting on the Greenland Ice Sheet is common up to ∼1400 m elevation and, in extreme melt years, even higher. Water produced on the ice sheet surface collects in lakes and drains over the ice sheet surface via supraglacial streams and through the ice sheet via moulins. Water delivered to the base of the ice sheet can cause uplift and enhanced sliding locally. Here we use ice-penetrating radar data to observe the effects of significant basal melting coincident with moulins and calculate how much basal melt occurred. We find that more melting has occurred than can be explained by the release of potential energy from the drainage of surface meltwater during one melt season suggesting that these moulins are persistent for multiple years. We find only a few persistent moulins in our study area that drain the equivalent of multiple lakes per year and likely remain active over several years. Our observations indicate that once established, these persistent moulins might be capable of establishing well-connected meltwater drainage pathways.

Received 26 September 2009; accepted 30 December 2009; published 29 January 2010.

A decrease in water vapor concentrations in parts of the middle atmosphere has contributed to a slowing of Earth’s warming, researchers are reporting. The finding, they said, offers part of the explanation for a string of years with relatively stable global surface temperatures.

Despite the decrease in water vapor, the study’s authors said, the overall trend is still toward a warming climate, primarily caused by a buildup in emissions of carbon dioxide and other heat-trapping gases from human sources.

“This doesn’t alter the fundamental conclusion that the world has warmed and that most of that warming has to do with greenhouse gas emissions caused by man," said Susan Solomon, a climate scientist at the National Oceanic and Atmospheric Administration and the lead author of the report, which appears in the January 29, 2010, issue of the journal Science.

Water vapor, a potent heat-trapping gas, absorbs sunlight and re-emits heat into Earth’s atmosphere. Its concentrations in the stratosphere, the second of three layers in the atmosphere, appear to have decreased in the last 10 years, according to the study.

This has slowed the rate of Earth’s warming by about 25 percent, Dr. Solomon said.

“We use the 10-10-10 to describe it,” she said. “That is, a 10 percent change in water vapor, 10 miles above our head, over the past 10 years.”

The study also found that from 1980 to 2000, an increase in water vapor sped the rate of warming — the result of an increase in emissions of methane, another greenhouse gas, during the industrial period. Methane, when oxidized, produces water vapor. Why a decrease in water vapor has occurred in the last 10 years is still unknown.

Dr. Solomon emphasized that the study focused on the atmosphere’s middle layer, not to be confused with the troposphere, Earth’s first layer. It has been known for years that water vapor in the troposphere amplifies the effect of greenhouse gas emissions.

Some climate skeptics have claimed that a spate of years with relatively stable temperatures indicates that the threat of global warming has been overblown.

Stratospheric water vapor concentrations decreased by about10% after the year 2000. Here, we show that this acted to slowthe rate of increase in global surface temperature over 2000-2009 by about 25% compared to that which would have occurreddue only to carbon dioxide and other greenhouse gases. Morelimited data suggest that stratospheric water vapor probablyincreased between 1980 and 2000, which would have enhanced thedecadal rate of surface warming during the 1990s by about 30%compared to estimates neglecting this change. These findingsshow that stratospheric water vapor represents an importantdriver of decadal global surface climate change.

New NASA-led research shows that the melt season for Arctic sea ice has lengthened by an average of 20 days over the span of 28 years, or 6.4 days per decade. The finding stems from scientists' work to compile the first comprehensive record of melt onset and freeze-up dates -- the "melt season" -- for the entire Arctic. Larger imageArctic sea ice has been facing longer melt seasons, according to a new study. Credit: NASA/Thorsten Markus

The melt season begins each April when the sunless winter gives way to sunrise and spring, and water and air temperatures rise. By September, the sea ice shrinks to a minimum and begins refreezing, bringing the annual melt season to an end.

The longer melt season, described by Thorsten Markus of NASA's Goddard Space Flight Center in Greenbelt, Md., in the Journal of Geophysical Research -- Oceans, has implications for the future of Arctic sea ice. Open water that appears earlier in the season absorbs more heat from the sun throughout summer, further warming the water and promoting more melting.

"This feedback process has always been present, yet with more extensive open water this feedback becomes even stronger and further boosts ice loss," Markus said. "Melt is starting earlier, but the trend towards a later freeze-up is even stronger because of this feedback effect." Larger imageResearchers analyzed satellite data for 10 different Arctic regions and found trends in melt and freeze onset days as well as trends in melt season length. Credit: NASA/Thorsten Markus

To examine melt season length, Markus and colleagues used data from satellite passive microwave sensors, which can "see" indications of melt. The result is an accurate account of the melt seasons from 1979 to 2007.

"Given that the Arctic ocean is nearly twice the size of the continental United States, it would be impossible to track change like this without long-term satellite records," said Thomas Wagner, NASA's cryosphere program scientist at NASA Headquarters, Washington.

Analyzing melt-season trends for 10 different Arctic regions, the research team discovered that melt season lengthened the most -- more than 10 days per decade -- in Hudson Bay, the East Greenland Sea, the Laptev and East Siberian Seas, and the Chukchi and Beaufort Seas. Some of that change is due to melt onset occurring about three days earlier per decade in some areas. Earlier melt means more heat can be absorbed by the open water, promoting more melting and later freeze-up dates -- more than eight days per decade later in some areas. Only the Sea of Okhotsk turned up a shorter melt season. The reasons for the regional differences are currently being investigated.

"The onset of melting and melt season length are important variables for understanding the Arctic climate system," Markus added. "Given the recent large losses of the Arctic summer ice cover, it has become critical to investigate the causes of the decline and the consequences of its continued decline."

The lengthened melt season could impact more than just the Arctic ice and ocean. According to Markus, "marine ecosystems are very sensitive to changes in melt onset and freeze-up dates."

Between 1979 and 2007, Arctic sea ice has begun melting (left map) an average of 2.8 days per decade earlier in the spring, and has begun re-freezing (center map) an average of 3.7 days per decade later in the autumn. Altogether, the length of the Arctic melt season (right map) has increased by about 20 days over the past 30 years. These maps are based on satellite observations of microwave energy radiated from the surface of sea ice. Credit: NASA images by Robert Simmon, based on data from Jeffrey Miller and Thorsten Markus.

"Changes in the Arctic sea ice cover may have profound effects on North America’s climate," said Wagner.

"Studies like this one show us how ice responds to variations in the ocean and atmosphere and improve the predictive models that will help us plan for climate change."

In order to explore changes and trends in the timing of Arctic sea ice melt onset and freezeup, and therefore melt season length, we developed a method that obtains this information directly from satellite passive microwave data, creating a consistent data set from 1979 through present. We furthermore distinguish between early melt (the first day of the year when melt is detected) and the first day of continuous melt. A similar distinction is made for the freezeup. Using this method we analyze trends in melt onset and freezeup for 10 different Arctic regions. In all regions except for the Sea of Okhotsk, which shows a very slight and statistically insignificant positive trend (0.4 d decade−1), trends in melt onset are negative, i.e., toward earlier melt. The trends range from −1.0 d decade−1 for the Bering Sea to −7.3 d decade−1 for the East Greenland Sea. Except for the Sea of Okhotsk all areas also show a trend toward later autumn freeze onset. The Chukchi/Beaufort seas and Laptev/East Siberian seas observe the strongest trends with 7 d decade−1. For the entire Arctic, the melt season length has increased by about 20 days over the last 30 years. Largest trends of over 10 d decade−1 are seen for Hudson Bay, the East Greenland Sea, the Laptev/East Siberian seas, and the Chukchi/Beaufort seas. Those trends are statistically significant at the 99% level.

Received 13 April 2009; accepted 4 September 2009; published 29 December 2009.

What's the deal with Antarctica?

by Brett Anderson, AccuWeather, January 27, 2010

A recent article from NASA's Earth Observatory claims that the latest data reveal that Antarctica is losing ice at an accelerating rate. But how can that be? Especially when one recent study claimed that there has been less surface melting on the giant ice sheet in recent years and the evidence that the amount of sea ice around Antarctica has been slightly increasing.

Wednesday, January 27, 2010

There has been lots of talk lately about Antarctica and whether or not the continent's giant ice sheet is melting. One new paper [1], which states there’s less surface melting recently than in past years, has been cited as "proof" that there’s no global warming. Other evidence that the amount of sea ice around Antarctica seems to be increasing slightly [2-4] is being used in the same way. But both of these data points are misleading. Gravity data collected from space using NASA's Grace satellite show that Antarctica has been losing more than a hundred cubic kilometers (24 cubic miles) of ice each year since 2002. The latest data reveal that Antarctica is losing ice at an accelerating rate, too. How is it possible for surface melting to decrease, but for the continent to lose mass anyway? The answer boils down to the fact that ice can flow without melting.

Two-thirds of Antarctica is a high, cold desert. Known as East Antarctica, this section has an average altitude of about 2 kilometers (1.2 miles), higher than the American Colorado Plateau. There is a continent about the size of Australia underneath all this ice; the ice sheet sitting on top averages at a little over 2 kilometers (1.2 miles) thick. If all of this ice melted, it would raise global sea level by about 60 meters (197 feet). But little, if any, surface warming is occurring over East Antarctica. Radar and laser-based satellite data show a little mass loss at the edges of East Antarctica, which is being partly offset by accumulation of snow in the interior, although a very recent result from the NASA/German Aerospace Center's Gravity Recovery and Climate Experiment (Grace) suggests that since 2006 there has been more ice loss from East Antarctica than previously thought [5]. Overall, not much is going on in East Antarctica -- yet.

West Antarctica is very different. Instead of a single continent, it is a series of islands covered by ice -- think of it as a frozen Hawaii, with penguins. Because it's a group of islands, much of the West Antarctic Ice Sheet (WAIS, in the jargon) is actually sitting on the floor of the Southern Ocean, not on dry land. Parts of it are more than 1.7 km (1 mile) below sea level. Pine Island is the largest of these islands and the largest ice stream in West Antarctica is called Pine Island Glacier. The WAIS, if it melted completely, would raise sea level by 5-7 m (16-23 feet). And the Pine Island Glacier would contribute about 10% of that.

Since the early 1990s, European and Canadian satellites have been collecting radar data from West Antarctica. These radar data can reveal ice motion and, by the late 1990s, there was enough data for scientists to measure the annual motion of the Pine Island Glacier. Using radar information collected between 1992 and 1996, oceanographer Eric Rignot, based at NASA’s Jet Propulsion Laboratory (JPL), found that the Pine Island Glacier's "grounding line" -- the line between the glacier's floating section and the part of the glacier that rests on the sea floor -- had retreated rapidly towards the land. That meant that the glacier was losing mass. He attributed the retreat to the warming waters around West Antarctica [6]. But with only a few years of data, he couldn't say whether the retreat was a temporary, natural anomaly or a longer-term trend from global warming.

Rignot's paper surprised many people. JPL scientist Ron Kwok saw it as demonstrating that "the old idea that glaciers move really slowly isn't true any more." One result was that a lot more people started to use the radar data to examine much more of Antarctica. A major review published in 2009 found that Rignot's Pine Island Glacier finding hadn't been a fluke [7]: a large majority of the marine glaciers of the Antarctic Peninsula were retreating, and their retreat was speeding up. This summer, a British group revisited the Pine Island Glacier finding and found that its rate of retreat had quadrupled between 1995 and 2006 [8].

The retreat of West Antarctica's glaciers is being accelerated by ice shelf collapse. Ice shelves are the part of a glacier that extends past the grounding line towards the ocean they are the most vulnerable to warming seas. A longstanding theory in glaciology is that these ice shelves tend to buttress (support the end wall of) glaciers, with their mass slowing the ice movement towards the sea, and this was confirmed by the spectacular collapse of the Rhode Island-sized Larsen B shelf along the Eastern edge of the Antarctic Peninsula in 2002. The disintegration, which was caught on camera by NASA's Moderate Resolution Imaging Spectroradiometer (MODIS) imaging instruments on board its Terra and Aqua satellites, was dramatic: it took just three weeks to crumble a 12,000-year-old ice shelf. Over the next few years, satellite radar data showed that some of the ice streams flowing behind Larsen B had accelerated significantly, while others, still supported by smaller ice shelves, had not [9]. This dynamic process of ice flowing downhill to the sea is what enables Antarctica to continue losing mass even as surface melting declines.

Michael Schodlok, a JPL scientist who models the way ice shelves and the ocean interact, says melting of the underside of the shelf is a prerequisite to these collapses. Thinning of the ice shelf reduces its buttressing effect on the glacier behind it, allowing glacier flow to speed up. The thinner shelf is also more likely to crack. In the summer, meltwater ponds on the surface can drain into the cracks. Since liquid water is denser than solid ice, enough meltwater on the surface can open the cracks up deeper down into the ice, leading to disintegration of the shelf. The oceans surrounding Antarctica have been warming [10], so Schodlok doesn't doubt that the ice shelves are being undermined by warmer water being brought up from the depths. But he admits that it hasn't been proven rigorously, because satellites can’t measure underneath the ice.

Glaciologist Robert Bindschadler of NASA's Goddard Space Flight Center intends to show just that. He's leading an expedition scheduled to start in 2011 to drill through the Pine Island Glacier and place an automated buoy into the water below it. According to Bindschadler, Pine Island Glacier "is the place to go because that is where the changes are the largest. If we want to understand how the ocean is impacting the ice sheet, go to where it's hitting the ice sheet with a sledgehammer, not with a little tack hammer."

Meanwhile, measurements from the Grace satellites confirm that Antarctica is losing mass [11]. Isabella Velicogna of JPL and the University of California, Irvine, uses Grace data to weigh the Antarctic ice sheet from space. Her work shows that the ice sheet is not only losing mass, but it is losing mass at an accelerating rate. "The important message is that it is not a linear trend. A linear trend means you have the same mass loss every year. The fact that it’s above linear, this is the important idea, that ice loss is increasing with time," she says. And she points out that it isn’t just the Grace data that show accelerating loss; the radar data do, too. "It isn't just one type of measurement. It's a series of independent measurements that are giving the same results, which makes it more robust."

Arctic climate is projected to change dramatically in the next 100 years and increases in temperature will likely lead to changes in the distribution and makeup of the Arctic biosphere. A largely deciduous ecosystem has been suggested as a possible landscape for future Arctic vegetation and is seen in paleo-records of warm times in the past. Here we use a global climate model with an interactive terrestrial biosphere to investigate the effects of adding deciduous trees on bare ground at high northern latitudes. We find that the top-of-atmosphere radiative imbalance from enhanced transpiration (associated with the expanded forest cover) is up to 1.5 times larger than the forcing due to albedo change from the forest. Furthermore, the greenhouse warming by additional water vapor melts sea-ice and triggers a positive feedback through changes in ocean albedo and evaporation. Land surface albedo change is considered to be the dominant mechanism by which trees directly modify climate at high-latitudes, but our findings suggest an additional mechanism through transpiration of water vapor and feedbacks from the ocean and sea-ice.

The upcoming ice age has been postponed indefinitely

by John Cook, Skeptical Science, January 27th, 2010

The 9th most popular skeptic argument is that we're heading into an ice age. The whole premise of the website Ice Age Now is that a new ice age could begin any day. Considering the skeptic aversion towards alarmism, it's surprising that this idea has gained so much traction. In the interest of lowering skeptics' stress levels, its time to put all those ice age fears to rest once and for all.

Just a few centuries ago, the planet experienced a mild ice age, quaintly dubbed the Little Ice Age. Part of the Little Ice Age coincided with a period of low solar activity termed the Maunder Minimum (named after astronomer Edward Maunder). It's believed that a combination of lower solar output and high volcanic activity were a major contributor (Free 1999, Crowley 2001), with changes in ocean circulation also having an effect on European temperatures (Mann 2002).

Figure 1. Total Solar Irradiance (TSI). TSI from 1880 to 1978 from Solanki. TSI from 1979 to 2009 from PMOD.

Could we be heading into another Maunder Minimum? Solar activity is currently showing a long term cooling trend. 2009 saw solar output at its lowest level in over a century. However, predicting future solar activity is problematic. The transition from a period of 'grand maxima' (the situation in the latter 20th century) to a 'grand minima' (e.g., Maunder Minimum conditions) is a chaotic process and difficult to predict (Usoskin, 2007).
Let's say for the sake of argument that the sun does enter another Maunder Minimum over the next century. What effect would this have on Earth's climate? The difference in solar radiative forcing between Maunder Minimum levels and current solar activity is estimated between 0.17 W/m2 (Wang, 2005) to 0.23 W/m2 (Krivova, 2007). In contrast, the radiative forcing of CO2 since pre-industrial times is 1.66 W/m2 (IPCC AR4), far outstripping solar influence. Add to this the extra CO2 emitted in upcoming decades and other greenhouse gases such as methane. The warming from man-made greenhouse gases far outstrips any potential cooling even if the sun was to return to Maunder Minimum levels.

However, our climate has experienced much more dramatic change than the Little Ice Age. Over the past 400,000 years, the planet has experienced ice age conditions, punctuated every 100,000 years or so by brief warm intervals. These warm periods, called interglacials, typically last around 10,000 years. Our current interglacial began around 11,000 years ago. Could we be on the brink of the end of our interglacial?

How do ice ages begin? Changes in the earth's orbit cause less sunlight (insolation) to fall on the northern hemisphere during summer. Northern ice sheets melt less during summer and gradually grow over thousands of years. This increases the Earth's albedo which amplifies the cooling, spreading the ice sheets further. This process lasts around 10,000 to 20,000 years, bringing the planet into an ice age.

Not all interglacials last the same amount of time. An ice core from Dome C, Antarctica offered a glimpse of temperatures going back 720,000 years. Climatic conditions 420,000 years ago were similar to current conditions. At that time, the interglacial lasted 28,000 years, suggesting our current interglacial may have lasted a similar period without human intervention (Augustin, 2004).

The similar conditions between now and 400,000 years ago are due to similar configurations in the Earth's orbit. At both times, the forcing from orbital variations showed much less change then in other interglacials. Simulations with the current orbit find that even without CO2 emissions, the current interglacial is expected to last at least 15,000 years (Berger, 2007).

Of course, the question of how long our interglacial lasts without human intervention is moot. We are intervening. So what effect do our CO2 emissions have on any future ice ages? This question is examined in one study that examines the glaciation "trigger" -- the required drop in summer northern insolation to begin the process of growing ice sheets (Archer 2005). The more CO2 there is in the atmosphere, the lower insolation needs to drop to trigger glaciation.

Figure 3 examines the climate response to various CO2 emission scenarios. The green line is the natural response without CO2 emissions. Blue represents an anthropogenic release of 300 gigatonnes of carbon -- we have already passed this mark. Release of 1000 gigatonnes of carbon (orange line) would prevent an ice age for 130,000 years. If anthropogenic carbon release were 5000 gigatonnes or more, glaciation will be avoided for at least half a million years. As things stand now, the combination of relatively weak orbital forcing and the long atmospheric lifetime of carbon dioxide is likely to generate a longer interglacial period than has been seen in the last 2.6 million years.

Figure 3. Effect of fossil fuel CO2 on the future evolution of global mean temperature. Green represents natural evolution, blue represents the results of anthropogenic release of 300 Gton C, orange is 1000 Gton C, and red is 5000 Gton C (Archer, 2005).
So we can rest assured, there is no ice age around the corner. To those with lingering doubts that an ice age might be imminent, turn your eyes towards the northern ice sheets. If they're growing, then yes, the 10,000 year process of glaciation may have begun. However, currently the Arctic permafrost is degrading, Arctic sea ice is melting and the Greenland ice sheet is losing mass at an accelerating rate. These are hardly good conditions for an imminent ice age.

Thanks to John Cross for putting me onto a few very relevant papers while preparing this post.

Despite a crippling recession and tight credit markets, the American wind power industry grew at a blistering pace in 2009, adding 39 percent more capacity. The country is close to the point where 2% of its electricity will come from wind turbines.

While that is still a small share, it is up from virtually nothing a few years ago. Continued growth at such a fast pace could help the nation lower its emissions of the gases that cause global warming.

The American Wind Energy Association, in its annual report to be released on Tuesday, said the amount of capacity added last year, 9,900 megawatts, was the largest on record, and was 18% above the capacity added in 2008, also a banner year.

The group said the growth of wind power was helped by the federal stimulus package that passed a year ago, which extended a tax credit and provided other investment incentives for the industry.

But the group warned that the growth could slow. Much of the wind development in 2009 was caused by momentum from 2008, as huge turbines ordered then were delivered to wind farms. In 2009, the recession idled many manufacturers and new orders weakened, which could portend an installation slowdown this year.

“The U.S. wind industry shattered all installation records in 2009, and this was directly attributable to the lifeline that was provided by the stimulus package,” said Denise Bode, the trade association’s chief executive. “The second half of the year was extraordinary. But manufacturers didn’t see much growth because they had built up so much inventory.”

About as much new power-generating capacity came from wind as from natural gas last year, Ms. Bode said. Together, new wind and natural gas projects accounted for about 80 percent of all new generating capacity added in the country.

The wind industry has undergone rapid growth in recent years. Since 2002, the country’s installed base of wind turbines has jumped almost sevenfold.

Even so, the American industry has lagged behind Europe, which gets about 5% of its electricity from wind. The European Commission has set an ambitious mandate to achieve 20% of electrical production from wind and other renewable sources by 2020. Denmark has essentially achieved that goal already, and sometimes produces more wind power than it can use.

Last year, China also outlined plans to more than double the country’s wind capacity by the end of this year by investing $14.6 billion, with rapid growth planned through the end of the decade.

Concerns about global warming have sparked interest in renewable power in the United States and spurred the creation of a domestic manufacturing industry that now employs 85,000 people. Today, about half the components used in wind farms are made in the United States, compared with 25% in 2004, the trade group said.

Much of the growth is attributable to state laws that mandate that a portion of the local power come from renewable sources. But many hurdles remain in getting to 10 or 20% wind power nationally.

Wind investors have called for long-distance transmission lines between the nation’s wind-intensive regions, mostly in the Great Plains and Texas, and its biggest population centers, mostly on the coasts. The lack of such transmission is seen as a major obstacle to further expansion.

“It is not a question of lack of resources,” said Tim Stephure, an analyst at Emerging Energy Research, a consulting firm in Cambridge, Mass. “Unlike the federal highway system or the national gas system, there is a huge lack of federal oversight for electricity. This is something that will take time, while the need for the industry is now.”

Still, the potential for wind is enormous. Mr. Stephure said that by 2020, wind’s installed capacity could be five times higher than it is today, reaching about 180,000 megawatts.

The industry has also called on Congress to pass a federal mandate requiring that a certain percentage of power come from renewable sources. Such mandates are already in place throughout the European Union and in China. In the United States, 29 states have adopted such a renewable power standard.

“The wind manufacturing sector has the potential to employ many more Americans in green jobs, but without a renewable electricity standard to provide a long-term market, the sector will be slow to grow,” the trade group said in its report.

The nation’s wind turbines generate enough electricity to power the equivalent of 9.7 million homes, according to the report. Last year, Texas consolidated its lead as the nation’s top wind producer, with a total capacity of 9,410 megawatts, about three times more than the second-largest producer, Iowa. They were followed by California, Washington and Minnesota.

Sunday, January 24, 2010

Sunday, 24 January, 2010

Peer reviewed impacts of global warming

If the IPCC's mistaken prediction that the Himalayan glaciers would be gone by 2035 taught us anything, it's that we should always source our information from peer reviewed scientific literature rather than media articles. Consequently, I've spent the weekend overhauling thelist of positives and negatives of global warming so that all sources were peer reviewed. The list is by no means comprehensive and I welcome any comments mentioning other impacts of global warming found in peer reviewed papers (good or bad). Please include a link to either the abstract or if possible, the full paper. Note to skeptics - here is an opportunity to pad out the positive column if you can find peer reviewed papers outlining any benefits of global warming.